Question

A balanced three phase, 300kVA,12kV,60 Hz delta connected system supplies 0.75 full load at a power factor of 0.8 lag to a balanced star connected load.

Determine:
The phase current of the source and line current.

Answer 1

The phase current of the source is 11.07 A in a balanced three-phase system with a power factor of 0.8 lag.

Step-by-step explanation:

In a balanced three-phase system, the line current is equal to the phase current. To determine the phase current of the source, we need to calculate the apparent power (S) using the formula:

S = VL x IL

where VL is the line voltage (12 kV) and IL is the line current. Since the power factor is 0.8 lag, the power factor angle (p) can be found using the formula:

cos p = 0.8

Solving for p gives p = cos^(-1)(0.8) = 36.86 degrees.

Now we can calculate the phase current IL:

IL = 0.75 x (300 kVA) / (sqrt(3) x VL x cos p)

Substituting the given values, we get IL = 11.07 A.